Intelligent CCHP System

ABSTRACT

Co-generating energy sources are controlled using a control system that monitors local and remote data. The local and remote data allow for energy management both in the short and long term by comparing the cost of using the co-generating energy source with other available energy sources. Individual co-generating energy sources can have their data aggregated and combined with remote data to allow for predictions of gross demand for energy. The gross demand can be used by an energy utility to plan for future energy needs and to negotiate with energy providers based upon those needs. The energy utility may control the individual co-generating energy sources so as to most cost-effectively meet the needs of the user of the individual co-generating energy source.

RELATED APPLICATION DATA

This application claims the benefit of priority of U.S. Provisional Patent Application No. 61/788,532 filed Mar. 15, 2013, and titled Dynamically Responsive High Efficiency CCHP System, U.S. Provisional Patent Application No. 61/788,300 filed Mar. 15, 2013, and titled System and Method of Regenerating Desulfurization Beds in a Fuel Cell System, U.S. Provisional Patent Application No. 61/781,965 and filed Mar. 14, 2013, and titled Power Conversion System with a DC to DC Boost Converter, and U.S. Provisional Patent Application No. 61/784,894 filed Mar. 14, 2013, and titled Hybrid Autothermal Steam Reformer for Fuel Cell Systems, each of which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of combined cooling, heating, and power systems. In particular, the present invention is directed to an intelligent combined cooling, heating, and power system.

BACKGROUND

Combined cooling, heating, and power (CCHP) systems can take on several forms and have been known to include fuel cells. A fuel cell is an electrochemical device which reacts hydrogen with oxygen to produce electricity and water. The basic process is highly efficient, and fuel cells fueled directly by hydrogen are substantially pollution-free. Moreover, as fuel cells can be assembled into stacks of various sizes, fuel cell systems have been developed to produce a wide range of electrical power output levels and thus can be employed in numerous applications.

Although the fundamental electrochemical processes involved in all fuel cells are well understood, engineering solutions have proved elusive for making efficient use of fuel cells, especially in residential and light commercial applications, where the power output demands of a fuel cell are not as significant. The prior art approach of sophisticated balance-of-plant systems are unsuitable for optimizing and maintaining relatively low power capacity applications and often result in wasted energy and systems that are not cost-effective.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, the drawings show aspects of one or more embodiments of the invention. However, it should be understood that the present invention is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:

FIG. 1 is a block diagram of an intelligent combined cooling, heating, and power system according to an embodiment of the present invention;

FIG. 2 is a block diagram of a fuel cell system according to an embodiment of the present invention;

FIG. 3 is a schematic of a high temperature polymer electrolyte membrane fuel cell according to an embodiment of the present invention;

FIG. 4 is a block diagram of a waste heat recovery system according to an embodiment of the present invention;

FIG. 5 is a block diagram of an intelligent combined cooling, heating, and power system according to another embodiment of the present invention;

FIG. 6 is a block diagram of a control system according to an embodiment of the present invention.

FIG. 7A is a block diagram of an internal data acquisition module according to an embodiment of the present invention;

FIG. 7B is a block diagram of an external data acquisition module according to an embodiment of the present invention;

FIG. 8 is a flow diagram illustrating a method of operating an intelligent combined cooling, heat, and power system according to an embodiment of the present invention;

FIG. 9 is a flow diagram illustrating a method of optimizing cost savings using an intelligent combined cooling, heating, and power system according to an embodiment of the present invention;

FIG. 10 is a flow diagram illustrating a method of managing fuel distribution of a plurality of intelligent combined cooling, heating, and power system systems according to an embodiment of the present invention; and

FIG. 11 is a block diagram of a computing environment that may be used to implement a combined cooling, heating, and power system according to an embodiment of the present invention.

DESCRIPTION OF THE DISCLOSURE

An intelligent combined cooling, heating, and power (CCHP) system according to the present disclosure dynamically generates high-efficiency power, heating, and/or cooling on demand or in response to a sensed load. The CCHP system of the present disclosure can be operated so as to produce high utilization of an electricity generating device such as, but not limited to, a fuel cell or group of fuel cells (often referred to as a “fuel cell stack”), using both the electric and thermal energy generated by the device for use within a structure throughout the year. In this way, the CCHP system provides near complete energy recovery. Operationally, a CCHP system according to one or more embodiments of the present disclosure allows for the use of readily available hydrocarbon fuels, such as natural gas or propane, near atmospheric pressure operation, close-coupled heating and cooling systems, optimized power electronics, drop-in replacement capabilities for existing heating, cooling, and hot water systems, and grid integration. A CCHP system according to one or more embodiments of the present invention can run in multiple modes of energy generation thereby allowing for the economic optimization of energy benefits (e.g., minimized costs and maximized profit to the user).

FIG. 1 shows an exemplary CCHP system 100 according to an embodiment of the present invention. At a high level, CCHP system 100 includes a power generation system such as a fuel cell system 104, a waste heat recovery system 108, and a control system 112. In operation, and as explained in more detail below. CCHP system 100 may include other co-generating devices, such as gas turbines, steam generators, or other engines. In FIG. 1, the embodiment includes fuel cell system 104, which uses a refined mixture of water, air, and hydrogen to produce electrical energy and thermal energy. As with most fuel cells, fuel cell system 104 must be kept within a predetermined temperature range in order to promote efficient operation of the cell. Thus, at least a portion of the thermal energy produced by fuel cell system 104 is removed by waste heat recovery system 108, which, as described more fully below, is designed and configured to make the fuel cell system's thermal energy available for both reuse within the fuel cell system as well as heating and cooling of the structure, e.g., residence, commercial building, etc., or other heat load, e.g., swimming pool, where CCHP system 100 resides.

FIG. 2 shows the primary components of an exemplary fuel cell system 104. As shown, fuel cell system 104 includes a fuel-air-water delivery (FAWD) module 116, a reactant processing module 120, a power generation module 124, and a power conditioning module 128.

At a high level, FAWD module 116 receives fuel, air, water, and heat as inputs, and produces a desulfurized, humidified fuel stream, i.e., a refined fuel stream 132, and heat as outputs. The fuel used in fuel cell system 104 generally varies by the type of fuel cell employed. For example, hydrogen, carbon monoxide, methanol, and dilute light hydrocarbons like methane (by itself or in the form of natural gas) are used by common fuel cell types. As discussed in more detail below, the type of fuel cell used effectively in fuel cell system 104 produces both electrical and thermal energy in sufficient amounts for use in the structure in which it is deployed. In an exemplary embodiment, a high temperature polymer electrolyte membrane (PEM) fuel cell is used in fuel cell system 104 and the input into FAWD module 116 is natural gas, which is generally readily commercially available, although other fuels could be used.

In an embodiment, FAWD module 116 can desulfurize the fuel (if necessary) by contacting the fuel with an adsorbent which preferentially adsorbs hydrogen sulfide, carbonyl sulfide, sulfur odorants, or combinations thereof at a selected temperature and pressure. In an alternative embodiment, FAWD module 116 can also include a hydrocarbon desulfurization bed, such as the hydrocarbon desulfurization bed described in Applicants' co-pending patent application entitled “System and Method of Regenerating Desulfurization Beds in a Fuel Cell System,” U.S. Provisional Application Ser. No. 61/788,300, filed on Mar. 15, 2013, which is incorporated by reference for its discussion of the same.

FAWD module 116 may also further condition the fuel by altering the water content of the fuel to an appropriate level for the fuel cell system 104. The humidity of the refined fuel stream 132 may be increased by increasing the water input to the FAWD.

The input rate, temperature, pressure, and output of FAWD module 116 are regulated via control system 112, described in more detail below, so as to be responsive to the needs of the structure (e.g., thermal and electrical loads) and to optimize the utilization and efficiency of the CCHP system 100.

FAWD module 116 supplies refined fuel stream 132 to reactant processing module 120. Reactant processing module 120 provides the conditions necessary to deliver a reformate stream 136 to power generation module 124 that contains primarily H₂, CO, CO₂, CH₁, N₂ and H₂O. The two reactions, which generally take place within reactant processing module 120 and convert the refined fuel stream into hydrogen, are shown in equations (1) and (2).

½O₂+CH₄→2H₂+CO  Equation (1):

H₂O+CH₄→3H₂+CO  Equation (2):

The reaction shown in equation (1) is sometimes referred to as catalytic partial oxidation (CPO). The reaction shown in equation (2) is generally referred to as steam reforming. Both reactions may be conducted at a temperature of about 100° C. in the presence of a catalyst such as platinum. Reactant processing module 120 may use either of these reactions separately or in combination. While the CPO reaction is exothermic, the steam reforming reaction is endothermic. Reactors utilizing both reactions to maintain a relative heat balance are sometimes referred to as autothermal (ATR) reactors.

As evident from equations (1) and (2), both reactions produce carbon monoxide (CO). Such CO is generally present in amounts greater than 10,000 parts per million (ppm). In certain embodiments, because of the high temperature at which reactant processing module 120 is operated, this CO generally does not affect the catalysts in the reactant processing module.

Notably, the use of a high-temperature PEM fuel cell (as opposed to a low temperature PEM fuel cell system (e.g., less than 100° C.) substantially avoids the problem of removing most of the CO from the reformate stream 136. Should additional CO removal be desired, however, reactant processing module 120 may employ additional reactions and processes to reduce the CO that is produced. For example, two additional reactions that may be used are shown in equations (3) and (4). The reaction shown in equation (3) is generally referred to as the shift reaction, and the reaction shown in equation (4) is generally referred to as preferential oxidation (PROX).

CO+H₂O→H₂CO₂  Equation (3):

CO+½O₂→CO₂  Equation (4):

Various catalysts and operating conditions are known for accomplishing the shift reaction. For example, the reaction may be conducted at a temperature from about 300-600° C. in the presence of supported platinum. Other catalysts and operating conditions are also known. Such systems operating in this temperature range are typically referred to as high temperature shift (HTS) systems. The shift reaction may also be conducted at lower temperatures, such as 100-300° C., in the presence of other catalysts such as, but not limited to, copper supported on transition metal oxides. Such systems operating in this temperature range are typically referred to as low temperature shift (LTS) systems.

The PROX reaction may also be used to further reduce CO. The PROX reaction is generally conducted at lower temperatures than the shift reaction, such as between about 100-200° C. Like the CPO reaction, the PROX reaction can also be conducted in the presence of an oxidation catalyst such as platinum. The PROX reaction can typically achieve CO levels less than about 100 ppm (e.g., less than 50 ppm). Reactant processing module 124 can include additional or alternatives steps than those listed above to remove CO as is known in the art, and it is known that other processes to remove CO may be used.

In addition to converting the refined fuel stream 132 for use within power generation module 124 and removing undesirable components, reactant processing module 120 also removes heat from refined fuel stream 132. In an exemplary embodiment, heat removal is provided by a thermal fluid loop (not shown), which acts as a heat exchanger to remove heat from refined fuel stream 132 before the stream exits as reformate stream 136. Additional exemplary reactant processing modules are described in U.S. Pat. Nos. 6,207,122, 6,190,623, and 6,132,689, which are hereby incorporated by reference for their description of the same. In an exemplary embodiment, reactant processing module 120 includes a hybrid autothermal steam reformer of the type described in Applicants' co-pending patent application entitled “Hybrid Autothermal Steam Reformer for Fuel Cell Systems,” U.S. Provisional Application Ser. No. 61/784,894, filed on Mar. 14, 2013, which is incorporated by reference for its disclosure of the same.

Reformate stream 136 is provided as an input to power generation module 124. Power generation module 124 is a device capable of producing electric power and concomitantly generating thermal energy. In an exemplary embodiment, power generation module 124, when operating, is capable of producing thermal energy at a temperature of between about 120° C. and about 190° C. In another exemplary embodiment, power generation module 124, when operating, is capable of producing thermal energy at about 1.5 kW of thermal energy per 1 kW of electrical energy. In another exemplary embodiment, power generation module 124 is a high temperature polymer electrolyte membrane (PEM) fuel cell (sometimes referred to as proton exchange membrane fuel cell), such as the PEM fuel cell 200 shown in FIG. 3.

In PEM fuel cell 200, a membrane 204, such as, but not limited to, a phosphoric acid-doped cross-linked porous polybenzimidazole membrane, permits only protons 216 to pass between an anode 208 and a cathode 212. At anode 208, reformate stream 136 from reactant processing module 120 is reacted to produce protons 216 that pass through membrane 204. The electrons 220 produced by this reaction travel through circuitry 224 that is external to PEM fuel cell 200 to form an electrical current. At cathode 212, oxygen is reduced and reacts with protons 216 to form water. The anodic and cathodic reactions are described by the following equations (1) and (2), respectively:

H₂→2H⁺+2e ⁻  Equation (1):

O₂+4H⁺+4e ⁻→2H₂O  Equation (2):

A typical single fuel cell has a terminal voltage of up to approximately one volt DC. For purposes of producing much larger voltages, several fuel cells may be assembled together to form an arrangement called a fuel cell stack—an arrangement in which the fuel cells are electrically coupled together in series to form a larger DC voltage (a voltage near 100 volts DC, for example) and thus to provide more power and more thermal energy. An exemplary description of a fuel cell stack is found in U.S. Pat. No. 6,534,210, titled “Auxiliary Convective Fuel Cell Stacks for Fuel Cell Power Generation Systems”, which is incorporated by reference for its discussion of the same. Typically, the fuel cell stack may include flow plates (graphite, composite, or metal plates, as examples) that are stacked one on top of the other. The flow plates may include various surface flow channels and orifices to, as examples, route the reactants and products through the fuel cell stack. In the instance of use of a fuel cell stack, several membranes 204 (each one being associated with a particular fuel cell) may be dispersed throughout the fuel cell stack between anodes 208 and cathodes 212 of different fuel cells. Electrically conductive gas diffusion layers (GDLs) 232 may be located on each side of each membrane 204 to act as a gas diffusion medium and in some cases to provide a support for fuel cell catalysts 228. In this manner, reactant gases from each side of the membrane 204 may pass along the flow channels and diffuse through the GDLs 232 to reach the membrane 204.

Returning to FIG. 2, power conditioning module 128 receives variable DC electrical energy produced by power generation module 124 and outputs conditioned DC or AC power, depending on the desired application of the output power. In an embodiment, power conditioning module 128 converts variable, low-voltage DC power from the power generation module 124 using a highly efficient, high boost ratio (e.g., >5:1), variable low voltage input, bi-directional DC-DC converter connected to a highly efficient bidirectional inverter connected to the electrical grid. An example of a highly efficient, high boost ratio, bi-directional DC-DC converter is found in Applicants' co-pending application entitled, “Power Conversion System with a DC to DC Boost Converter”, U.S. Provisional Application Ser. No. 61/781,965, filed on Mar. 14, 2013, which is incorporated by reference for its discussion of the same. Power conditioning module 128 may also be designed and configured to provide conditioned power to the structure, for example, for residential uses. In another embodiment, power conditioning module 128 conditions power for both local loads, e.g., battery-powered cars, battery strings, other residential or light commercial loads, and for the electric grid. In this embodiment, if local loads are not high enough to use all of the power produced by the power generation module 124, the excess electrical power is conditioned for input to the electric grid.

As discussed previously, CCHP system 100 includes a waste heat recovery system 108. At a high level waste heat recovery system 108 is designed to recovery thermal energy from the power generator, such as fuel cell 104, which can be used by other components of CCHP system 100, or external to the system. An exemplary embodiment of a waste heat recovery system 108 designed for use with a fuel cell, such as fuel cell 104, is shown in FIG. 4. Waste heat recovery system 108 includes a thermal management module 144, a burner module 148, a cooling system 152, and a distribution system 156.

Thermal management module (TMM) 144 assists in controlling the operating temperatures of FAWD 108, reactant processing module 120, and power generation module 124, and directs thermal energy, as needed by the structure, to cooling system 152, and distribution system 156. TMM 144 manages the heat distribution throughout CCHP system 100 primarily via a heat transfer loop 140. Heat transfer loop 140 includes valves and pumps (not shown) that are controlled by control system 112 so as to provide the proper rate of fluid flow in the heat transfer loop. Metrics that are considered in determining the rate of fluid flow include, but are not limited to, a pump speed, a fuel cell stack inlet temperature, a fuel cell stack outlet temperature, a valve setting, and a return temperature from heat transfer loop 140, so as to provide efficient heat generation and distribution.

In an exemplary embodiment, the rate of fluid flow is determined by receiving a command for heating or cooling to a load in need thereof and providing stored heat or cooling to the load. If stored capacity is unable to satisfy the load demand from storage, burner module 148 (discussed further below) provides heat to heat transfer loop 140. Heat transfer loop 140 is used to heat the power generation module, reactant processing module 120, and heating and/or cooling system. In this embodiment, control system 112 can receive signals indicative of, for example, temperature inside the structure, the temperature outside the structure, and can use algorithms based on these signals to determine whether to start the fuel cell and export power. If the fuel cell needs to be operated, fuel flows to FAWD module 116 and reactant processing module 120. Once reformate stream 132 is of sufficient quality, it is delivered to the fuel cell, which begins to generate power and send heat to heat transfer loop 140. Control system 112 monitors temperature in heat transfer loop 140 and if necessary for heating or cooling, turns burner module 148 up, down or off as appropriate. In an exemplary embodiment, peak heating or cooling demands are by controlling burner module 148 rather than oversizing the rest of CCHP system 100.

Burner module 148 generates on-demand heat for use in the structure, provides auxiliary heat for subsystems during the startup of reactant processing module 120 and power generation module 124, provides auxiliary heat for special operations, provides peak heat for application heating and cooling loads, and assists in completing the combustion of unburned hydrocarbons, volatile organic compounds or carbon monoxide in the exhaust stream coming from FAWD module 116 as well as the reactant processing and power generation modules. Burner module 148 is monitored for burn temperatures to ensure substantially complete combustion of exhaust gases.

Cooling system 152 is used to deliver conditioned air to the structure. In an exemplary embodiment, cooling system 152 includes a reactor and an evaporator (not shown). Reactor contains an active substance, such as salt, and evaporator contains a volatile, absorbable liquid, such as water. At a high level, the operation of this exemplary cooling system 152 is as follows: (1) heat from TMM 144 is delivered to reactor and hence absorbed water is expelled from the reactor to the condenser, (2) when cooling is desired, a vacuum is applied to the evaporator, the water begins to rapidly be removed from the evaporator, and the remaining water gets colder. By coupling a coiled tube proximate to the evaporator, a liquid can be cooled and subsequently used for cooling within the structure.

Distribution system 156 manages the heat provided by TMM 144 to the application (e.g., residence, light industrial). In an exemplary embodiment, distribution system 156 includes appropriate fan/pump and connected ducting/piping to provide heat to the structure.

Control system 112 is generally configured to control the operation of CCHP system 100 and as such, controls the energy producing components of CCHP system 100, i.e., fuel cell 104, such that the components are responsive to user demand-increasing and decreasing output as desired (referred to herein as “load-following design”). In certain embodiments, control system 112 may also assist in determining the most cost-effective mode of operation, i.e., a heating mode, a cooling mode, and/or an electric power generation mode, of the CCHP system while meeting the user's electricity, heating, and cooling needs, or the user's monetary goals. For example, and as discussed in more detail below, control system 112 can direct CCHP system 100 to generate power for export to the grid, while simultaneously providing heat to the user's residence. The power exported to the grid may result in financial remuneration to the user through incentives offered by their power supplier.

In another exemplary embodiment, control system 112 facilitates the generation of multiple types of energy while minimizing energy costs (described further below with reference to FIG. 9). Control system 112 can also incorporate processes such as, but not limited to, processes 500 (shown in FIG. 8), 600 (as shown in FIG. 9), or 700 (as shown in FIG. 10), to determine the most cost-effective mode of operation depending on the energy needed by the user and external information.

Another embodiment of a CCHP system according to the present disclosure is shown in FIG. 5. In this embodiment, CCHP 300 includes the primary components of CCHP 100 (not labeled for clarity) in a single structure or enclosure 304, which can be sized and configured to drop in as a replacement for a traditional heating, cooling, and water heating unit. Auxiliary components, such as auxiliary heating equipment 308, auxiliary power equipment 312, and auxiliary cooling equipment 316, while including items such as duct work for distributing heated air throughout a structure, are each also typically designed and configured such that the CCHP 300 is not “over-designed”. For example, CCHP 300 may be designed to heat the structure in which it resides on all but the 3% of coldest days and to rely on the auxiliary heating equipment 308 to provide the additional heat on those days. In this way, CCHP 300 is not overdesigned by being sized to handle all possible heating loads. Similarly, CCHP 300 need not be designed to meet all possible cooling or power loads, as auxiliary cooling equipment 316 and auxiliary power equipment 312 can assist during peak demand times.

In certain embodiments, control system 112 may receive, in addition to operational information from CCHP 100 (as shown in FIG. 5) as inputs, external data from external data sources. Examples of external data sources include, but are not limited to, environmental data, Internet data, and long-term user data. External data may be input into a data management module residing within control system 112, such as data management module 312, described further below with reference to FIG. 6. External data may be used to refine the outputs of CCHP system 100, thereby more effectively meeting the user's needs. Data processing module 312 can deliver information, such as, but not limited to, external data, modified external data, and data derived from external data, to control system 112, which can configured to identify patterns in the information provided by the data processing module and to “learn” from the information and to improve the economic efficiency of CCHP system 100. Thus, the load-following design combined with the information analysis capabilities of control system 112 results in a more economical CCHP system.

Moreover, and in general, for fuel cell system 104, power generation is increased by raising fuel and air flow to the fuel cell in proportion to the stoichiometric ratios dictated by the equations listed above. Thus, in an exemplary embodiment control system 112 may monitor, among other things, the output power of power generation module 124 and/or the thermal energy output, and based on the monitored output power and voltage of the fuel cell, estimate the fuel and air flows required to satisfy the power demand by the thermal or electrical load of the structure.

As briefly discussed above, CCHP system 100 may provide power to a load, such as a load that is generated by residential appliances and electrical devices that may be selectively turned on and off to vary the power that is demanded. Thus, in some applications the electric load required of CCHP system 100 may not be constant, but rather the power that is consumed by the load may vary over time and/or change abruptly. Moreover, thermal loads required by the structure, such as heating requirements in the fall and winter months or cooling requirements in the summer, with or without electric load demands, may place different demands on the CCHP system 100. The availability of power and thermal capacity from CCHP system 100 is also controlled by control system 112.

FIG. 6 shows an exemplary embodiment of control system 112, control system 400. At a high level, control system 400 includes a local data acquisition module 404, a remote data acquisition module 408, a data management module 412 that can include a diagnostic module 416, a data processing unit 418, and a user interface 420.

Local data acquisition module 404 receives information from sensors (not shown) that are in communication with and transmit the characteristics of the components of CCHP system 100 and/or the structure, e.g., residence, commercial building, in which the CCHP system resides. Although discussed in more detail below with reference to FIG. 7, local data acquisition module 404 may receive information including, but not limited to, CCHP system 100 hardware capabilities and component operating conditions, available external power generation and the status of storage devices, power and heating/cooling loads, exterior and interior temperature, and the local date and time.

Remote data acquisition module 408 receives external inputs such as, but not limited to, electricity and gas prices. Remote data acquisition module 408 may receive its external inputs via a connection to the internet or from the sources of the external data, such as an electric utility. In an exemplary embodiment, remote data acquisition module 408 provides cost predictions based upon the external data by extrapolating from current prices and identifying prior trends in prices.

FIGS. 7A-B show an exemplary embodiment of the inputs that may be received by local data acquisition module 404 (FIG. 7A) or remote data acquisition module 408 (FIG. 7B). For example, local data acquisition module 404 can receive operational data 424 from the components of CCHP system 100 including internal characteristics or operating conditions. For example, local data acquisition module 404 can receive a reactant processing temperature, a FAWD blower/pump speed, a TMM temperature, a TMM pump speed, a stack inlet temperature, a stack outlet temperature, a valve setting, a stack voltage, a stack DC power output, an inverter power output, an air mass flow rate, and a fuel mass flow rate. Local data acquisition module 404 can also receive hardware configuration data 428, such as, but not limited to, a start-up time, a current system efficiency rating, a system ramp up/down capability, an electricity-generating system size, and a storage system size.

Remote data acquisition module 408 can receive data from generally outside the structure and device. External data can include a location data 432 (e.g., local weather input, time, date, etc.), a user data 436 (e.g., a heat demand, a cooling demand, a hot water demand, and an electrical load demand), an external power generation data 440, and a price data 444 (cost of electricity or fuel). User data 436 may be generated when, for example, the user sets the ambient zone temperature, requests hot water, or activates an electric appliance. External power generation data 440 can include, but are not limited to, a size and a list of other available power sources (including no-cost sources, such as solar, wind, hydro, and batteries), an indicator of the ability or inability to export to the electrical power grid, a local market value of power exported to the grid, and an external power generator profile.

Returning now to FIG. 6, as discussed above, data management module 412 receives data and information from local data acquisition module 404 and remote data acquisition module 408 and outputs commands to the components of CCHP system 100. In an exemplary embodiment, data management module 412 includes a data processing unit 418 for processing the data and information received by data management module 412. Data processing unit 418 can compile long-term user data in the form of profiles, such as, but not limited to, a heat profile, a cooling profile, an electricity profile, and a historical customer data profile. Control system 400 may apply one or more of profiles to predict, and more effectively respond to, user demands.

In an exemplary embodiment of control system 400, the control system can transmit the profiles mentioned above to a manufacturer/operator of CCHP system 100, enabling a manufacturer/operator of the CCHP system to predict long-term fuel and power usage. In another exemplary embodiment, a manufacturer/operator may be able to collect information and profiles from a plurality of CCHP systems 100 and therefore to predict, in the aggregate, the combined power producing capability of a plurality of CCHP systems and the expectant fuel usage.

Data processing unit 418 can also use programmed algorithms, set points, and lookup tables to determine operating parameters for CCHP system 100 components and/or to generate external data for use in evaluating the efficiency, lifespan, or diagnosing problems with the CCHP system. In setting the operating parameters for CCHP system 100, data processing unit 418 may determine the optimal operating conditions for the CCHP system and its cost-effectiveness relative to other sources of power. In an exemplary embodiment, data processing unit 418 concomitantly evaluates the availability and capacity of no-cost power sources (e.g., solar panels, wind turbines, etc.), the cost of fuel (e.g., natural gas or propane), electricity rates, and the economic benefit of exporting energy to the grid in determining whether to co-produce power and heating/cooling with CCHP system 100 or generate/purchase power from an external source. For example, data processing unit 418 may determine that although the structure has a current heat load that could be satisfied by CCHP system 100, because of the availability of lower cost fuel and the lack of electrical demand from the structure, it would be more cost effective to run an auxiliary heater to meet the heat load rather than operate the CCHP System. Processes 500 and 600, shown in FIGS. 8 and 9, respectively, are exemplary embodiments of this evaluative process and are discussed in more detail below.

Diagnostic module 416 can collect and transmit user and CCHP system 100 data to a fuel and/or electrical supplier/manufacturer/operator to allow them to collect usage and demand data, improve system performance, conduct maintenance reviews, and to allow the transmission of operational instructions to control system 400 via user interface 420 or remotely via external communication devices (not shown). Diagnostic module 416 can also report user and power generator data from each CCHP system 100 to a manufacturer/operator, allowing the fuel and/or electrical supplier/manufacturer/operator to predict long-term trends in fuel and electricity usage. As shown in FIG. 10 and explained in more detail below, this information can facilitate the fuel and/or electrical supplier/manufacturer/operator becoming a micro-utility-supplying fuel (e.g., natural gas or propane) and/or electricity to customers at lower cost by locking in fuel and/or electricity volumes at lower prices based upon understood usage trends of CCHP system(s) 100.

Although control system 112 or control system 400 is presently described as a separate component of CCHP system 100, it is understood that any control system can be dispersed among the various components described herein without affecting the function of the CCHP system. Among the advantages of one or more of the exemplary CCHP systems as described herein are:

1. The CCHP system can allow for high utilization (approaching, and at times including, 100%) of the fuel cell, allowing for substantial use of the electric and thermal power during varying electric and thermal load conditions. In an exemplary embodiment, the CCHP system can allow utilization of the fuel cell approaching 100%.

2. Substantial energy recovery is achieved by storing thermal energy produced by the fuel cell system.

3. The CCHP system is capable of using readily available hydrocarbon fuels such as natural gas and propane instead of expensive, difficult-to-obtain fuels such as hydrogen or methanol. Moreover, the use of high-temperature PEM fuel cells, as proposed herein, lessens the need for expensive steam or low efficiency, low temperature shift reformers.

4. The CCHP system can operate near atmospheric pressure, thereby increasing the system efficiency of the appliance by reducing parasitic losses from compressors and blowers (sometimes used to increase power density by pressurizing feed streams and/or to manage liquid water in the system). For example, the CCHP system is about 20% more efficient than similar systems that use compressors. The CCHP system does not require liquid water management, and power density is traded off for system efficiency.

5. The CCHP system uses close-coupled heating and cooling systems, which share plumbing and heat transfer media, thereby creating a simple, integrated appliance.

6. The CCHP system can include optimized power electronics, such as power conditioning system 120, which assists in maximizing power generation, extending fuel cell stack life, and providing high system efficiency.

7. The CCHP system is designed and configured as a drop-in replacement for existing heating, cooling, and hot water systems, thereby reducing the expense of using the CCHP system as a replacement. Moreover, by using the grid to supplement the CCHP system during peak load, the most expensive component in the system, the fuel cell system, can be right-sized for maximum utilization, rather than sizing the fuel cell system for peak load power usage (ensuring an over-capacity component that is challenged to return its capital cost) or under-sizing the fuel cell system such that it runs beneath the power usage profile of the application.

8. The CCHP system maximizes consumer comfort while minimizing cost. By continuously evaluating the availability and capacity of no-cost power sources, costs of fuel and electricity, and the market value of power sold back to the grid, the CCHP system can determine the least expensive option to meet the consumer's comfort needs.

9. The CCHP system reports user information back to the supplier/manufacturer/operator, improving CCHP system maintenance and allowing the supplier/manufacturer/operator to make long-term predictions of fuel and/or electricity demands to broker fuel and/or electricity rate purchases from wholesale suppliers with significantly reduced risk.

Turning now to an exemplary operation of CCHP system 100, and with reference to exemplary embodiments shown in FIGS. 1-7 and in addition with reference to FIG. 8, there is shown a process 500 according to an embodiment of the present disclosure.

At step 504, there is a determination of the load of the structure or outside load or both. In this embodiment, “load” may mean electrical power needs, heating needs, or cooling needs, or any combination of the same. The load may be determined by a control system, such as control system 112, which monitors activity in the structure such as, but not limited to, activation of machinery or appliances, changes in temperature within the structure or external to the structure, or via preprogrammed routines, or any combination of the aforementioned. Control system 112 may also receive external information, such as that the power rebates from the provision of power to the utility grid are beneficial to generate power for delivery to the grid.

At step 508, there is a determination as to which energy sources would be necessary to meet the load demands of the structure/outside load. In certain embodiments, there may be multiple simultaneous load demands of different types.

At step 512, energy is provided to meet the load demand. For example, power may be produced by a CCHP, such as CCHP system 100, in order to meet electrical load demands of the structure.

At step 516, the co-produced energy, i.e., heat or cooling if electrical power is needed or electrical power if heat or cooling is need, is delivered and/or stored. For example, if the structure is demanding electrical load, but no other load is required, a CCHP system may store the heat generated by operating the fuel cell system in the cooling system for later use. Alternatively, excess heat may be stored in a water tank or other heat sink for later use. If heat is needed, but power is not, the electrical energy produced by the fuel cell may be delivered to the electrical grid.

In another embodiment, a CCHP system, such as CCHP system 100, may operate according to process 600 as depicted in FIG. 9 so as to cost-effectively determine which, among a plurality of energy sources, should be used to meet a given load or multiple loads.

At step 604, one or more loads are determined. The load may be an electrical load of the structure or an external load, e.g., electric grid demand, or both; and/or a thermal load, i.e., a heating load or a cooling load. The load amount may be determined by a control system, such as control system 112, which monitors activity in the structure such as, but not limited to, activation of machinery or appliances, or via preprogrammed routines or preset threshold values (temperature settings), or a combination of the aforementioned. The load may also be a request from a user made using, for example, user interface 320.

At step 608, the energy sources available to meet the load(s) are determined. For example, power may be provided by other alternative sources to the CCHP system such as, a wind turbine, a solar array, a hydro turbine, or a battery array. Under certain conditions, one or more of the alternative energy sources may not be available or only intermittently available, for example, if a wind turbine is intermittently in service due to a lack of sustained winds. Accordingly, in certain embodiments of process 600, the availability of energy sources may be reevaluated for possible alternatives to those in use to meet the current load demands.

At step 612 the energy source(s) best able to meet the load(s) is determined. In some cases, this may be a no or low cost energy source, such as a solar array. In other instances it may be more cost effective to employ a CCHP to produce power sufficient to meet the demand while exporting some power to the electrical grid to receive monetary remuneration for the excess power. In still other instances, it may be combination of energy sources. For example, if power and thermal loads are present, but power requirements outpace heat load requirements, a CCHP system may be employed to meet the heat load and partial power load, while another power source, such as a solar array or the electrical grid, may be employed to meet the remaining power demand.

In an exemplary, embodiment of process 600, a determination of which energy sources to use to meet either an electrical, thermal, or electrical and thermal load includes comparing of market prices of electric power and fuel to the costs of generating the energy using the energy sources. Thus, for example, at step 616 a determination is made as to whether the load is electrical. If the load is electrical, process 600 continues to step 620, where a comparison is made between the price/cost of electricity from an electric utility and the cost of generating power with available electrical energy sources, such as CCHP system 100, a battery array, wind turbine, etc. If no electrical load is present, process 600 continues to step 628, where a comparison is made between the cost of fuel and the cost of generating thermal energy from other energy sources, such as CCHP system 100. The output of steps 620 and 628 may be used to evaluate which is the more cost effective energy source to employ in order to meet the load demands; however, the output could also be one factor among others, such as the relative carbon emissions of the available energy sources.

Returning to step 620, after determining an appropriate electric energy source, process 600 then determines whether a thermal load is also present at step 624. If no thermal load is present, step 612 determines which electrical producing energy source to employ. If a thermal load is present, process 600 proceeds to step 628 and a comparison, as discussed above, is conducted to arrive at the proper energy source to use to meet both the thermal and electrical loads.

In another embodiment of process 600, additional factors may influence the choice of which energy source to employ to meet a given load. For example, the existence of renewable energy credits, carbon offsets, energy purchase plans, and/or thermal or electrical storage capacity can affect the determination of energy source. Moreover, a user can specify or weight one energy source over another.

Turning now to FIG. 10, a CCHP system, such as CCHP system 100, when configured as described herein, can offer the ability for an energy/service provider (or other entity controlling or managing a number of CCHP systems) to register as fuel and/or electric utility, such as a natural gas, propane or electrical utility, and purchase fuel and electricity at wholesale prices, based on length of contract, and resell to individual CCHP system users at retail, or below retail, prices. By becoming a fuel and/or electric utility, the fuel and/or electricity supplier can establish revenue streams wherein it not only installs and services individual CCHP systems, but also provides all of the fuel and/or electricity required for each structure and operation of each CCHP system.

Process 700 allows for the efficient and cost-effective management of a distributed fleet of CCHP users (a group of residential and light commercial customers having CCHP systems, such as CCHP system 100). Process 700 also allows a fuel/electricity (energy) supplier to manage energy purchases while meeting individual user demands.

At step 704, the energy supplier receives information from each CCHP system such as, but not limited to, energy usage and demands. In another exemplary embodiment, step 704 includes a method of receiving, processing and reporting data regarding consumers' usage of its CCHP system and historic customer related, but non-customer specific, independent variable data for large batches of consumers for the purposes of managing the volume and price risks associated with each consumer. Customer usage data could include, for example, historic usage, demand levels, and dollars billed. Independent data may include, for example, heating degree days, cooling degree days, relative humidity, dew point, atmospheric pressure and precipitation. These data may be obtained and transmitted via a control system, such as control system 112 or 400, over a communication link such as, for example, the Internet, telephone lines or by computer readable media such as, for example, magnetic or optical storage media. Distribution can also be accomplished by distribution to a central storage site on the public Internet, an intranet, a local area network (LAN), a wide area network (WAN) or a direct connection for further access or distribution.

Customer-specific and the non-customer-specific data may be missing some data points or contain gross inaccuracies. Detection of missing or grossly inaccurate data points may be determined by the system described herein, and inaccuracies may be filled in using a variety of algorithms including, but not limited to, regressions, average replacements, deltas off of adjacent weather stations in the case of an energy capped bill, deltas off of prior points, average prior and subsequent point and strategic estimates.

At step 708, the information obtained from step 704 is used to predict individual CCHP system users' energy demands. The prediction can be based upon past usage and demand information alone or in combination with other, additional variables, such as predicted weather patterns, census data, energy consumption trends, etc. In an exemplary embodiment, an energy demand model for each CCHP system may be determined from customer information and other information such as, but not limited to, weather, vacations, etc. The determinations may also include, but are not limited to, the analysis of base non-weather related use, usage sensitivity to changes in weather, temperatures at which the consumer requires heating and/or cooling load, humidity, precipitation, wind speed, cloud cover, and trend variables (improvements in energy efficiency across the population, age of housing stock, etc.). In this way, a large number of individual consumers' information, including the individual models, maybe aggregated to determine price efficiency and risk management.

At step 712, the predictions developed in step 708 are aggregated so as to determine gross predictions. Gross predictions may be completed using group method data handling (GMDH) or other predictive modeling techniques capable of using large multivariable data sets. Using these gross predictions, the energy supplier may negotiate long-term wholesale fuel and electric purchases, locking in energy supplies at low prices. All customer usage data to be processed can include electronic data regarding anywhere from, for example, a few dozen to several million individual CCHP systems.

At step 716, the energy supplier may communicate directly with the individual CCHP control systems to manage fuel and electricity usage, conserving or accelerating the use of fuel and/or electricity (and utilizing external power sources) when consumption exceeds or lags predictions and using more or less fuel (co-producing power and heating with the CCHP unit rather than utilizing external power generators) when consumption fails to meet predictions.

Additionally, in an increasing number of jurisdictions, a CCHP system energy supplier can establish itself as both a fuel utility and an electric utility, enabling the fuel supplier to compare wholesale fuel prices with wholesale electricity market pricing. In an exemplary embodiment, the energy supplier can determine the optimum savings/earnings for the customer and energy supplier by comparing prices in the fuel and electricity markets. For example, if the wholesale price of electricity exceeds the cost of fuel necessary to produce it, then the fuel supplier can use previously purchased fuel and sell electricity, earning a net profit on the transaction. If, on the other hand, the cost of fuel exceeds the cost of electricity it would produce, the fuel supplier can concomitantly sell fuel and purchase electricity from the electric grid, earning a net profit on the transaction. This business model relies on an on-site, controllable power generating device, such as the CCHP device described herein, fueled by natural gas or other commodity fuel such as propane, allowing consumption prediction and flexing between two commodity markets: fuel and electricity.

In an additional exemplary embodiment, an energy provider that is established as both a fuel and electric utility may have several systems, such as CCHP system 100, installed in homes or light commercial applications (collectively, the “fleet”). Usage prediction and wholesale commodity purchasing are aggregated and employed as described above. The energy provider may now employ the fleet in a way which provides the optimum economic benefit to the consumer and the energy provider. Taking into account and meeting each individual energy need (heating, cooling, hot water and power) the fleet can take advantage of the price differences in the fuel and electricity markets to either consume or conserve fuel and generate or not generate electricity, solving for the best economic outcome and avoiding any penalties from incorrect predictions and commodity purchases.

In another exemplary embodiment, the CCHP system can be employed by the energy provider as a “peaker”, providing heating, cooling and hot water to an application with electricity needs significantly exceeding the system's capacity. Monitoring the spot price of electricity and fuel the energy provider can produce power when it is economically feasible to do so.

FIG. 8 shows a diagrammatic representation of one implementation of a machine/computing device 800 that can be used to implement a set of instructions for causing one or more control systems of CCHP system 100, for example, device 800, to perform any one or more of the aspects and/or methodologies of the present disclosure. Device 800 includes a processor 805 and a memory 810 that communicate with each other, and with other components, such as control system 112, fuel cell system 104, or waste heat recovery system 108, via a bus 815. Bus 815 may include any of several types of communication structures including, but not limited to, a memory bus, a memory controller, a peripheral bus, a local bus, and any combinations thereof, using any of a variety of architectures.

Memory 810 may include various components (e.g., machine-readable media) including, but not limited to, a random access memory component (e.g, a static RAM “SRAM”, a dynamic RAM “DRAM”, etc.), a read-only component, and any combinations thereof. In one example, a basic input/output system 820 (BIOS), including basic routines that help to transfer information between elements within device 800, such as during start-up, may be stored in memory 810. Memory 810 may also include (e.g., stored on one or more machine-readable media) instructions (e.g., software) 825 embodying any one or more of the aspects and/or methodologies of the present disclosure. In another example, memory 810 may further include any number of program modules including, but not limited to, an operating system, one or more application programs, other program modules, program data, and any combinations thereof.

Device 800 may also include a storage device 830. Examples of a storage device (e.g., storage device 830) include, but are not limited to, a hard disk drive for reading from and/or writing to a hard disk, a magnetic disk drive for reading from and/or writing to a removable magnetic disk, an optical disk drive for reading from and/or writing to an optical media (e.g., a CD, a DVD, etc.), a solid-state memory device, and any combinations thereof. Storage device 830 may be connected to bus 815 by an appropriate interface (not shown). Example interfaces include, but are not limited to, SCSI, advanced technology attachment (ATA), serial ATA, universal serial bus (USB), IEEE 1395 (FIREWIRE), and any combinations thereof. In one example, storage device 830 may be removably interfaced with device 800 (e.g., via an external port connector (not shown)). Particularly, storage device 830 and an associated machine-readable medium 835 may provide nonvolatile and/or volatile storage of machine-readable instructions, data structures, program modules, and/or other data for device 800. In one example, instructions 825 may reside, completely or partially, within machine-readable medium 835. In another example, instructions 825 may reside, completely or partially, within processor 805.

Device 800 may also include a connection to one or more systems or modules included with CCHP system 100. Any system or device may be interfaced to bus 815 via any of a variety of interfaces (not shown) including, but not limited to, a serial interface, a parallel interface, a game port, a USB interface, a FIREWIRE interface, a direct connection to bus 815, and any combinations thereof. Alternatively, in one example, a user of device 800 may enter commands and/or other information into device 800 via an input device, such as user interface 324. Examples of an input device include, but are not limited to, an alpha-numeric input device (e.g., a keyboard), a pointing device, a joystick, a gamepad, an audio input device (e.g., a microphone, a voice response system, etc.), a cursor control device (e.g., a mouse), a touchpad, an optical scanner, a video capture device (e.g., a still camera, a video camera), touchscreen, and any combinations thereof.

A user may also input commands and/or other information to device 800 via storage device 830 (e.g., a removable disk drive, a flash drive, etc.) and/or a network interface device 845. A network interface device, such as network interface device 845, may be utilized for connecting device 800 to one or more of a variety of networks, such as network 850, and one or more remote devices 855 connected thereto. Examples of a network interface device include, but are not limited to, a network interface card, a modem, and any combination thereof. Examples of a network include, but are not limited to, a wide area network (e.g., the Internet, an enterprise network), a local area network (e.g., a network associated with an office, a building, a campus, or other relatively small geographic space), a telephone network, a direct connection between two computing devices, and any combinations thereof. A network, such as network 850, may employ a wired and/or a wireless mode of communication. In general, any network topology may be used. Information (e.g., data, instructions 825, etc.) may be communicated to and/or from device 800 via network interface device 855.

Device 800 may further include a video display adapter 860 for communicating a displayable image to a display device 865. Examples of a display device 865 include, but are not limited to, a liquid crystal display (LCD), a cathode ray tube (CRT), a plasma display, and any combinations thereof.

In addition to display device 865, device 800 may include a connection to one or more other peripheral output devices including, but not limited to, an audio speaker, a printer, and any combinations thereof. Peripheral output devices may be connected to bus 815 via a peripheral interface 870. Examples of a peripheral interface include, but are not limited to, a serial port, a USB connection, a FIREWIRE connection, a parallel connection, a wireless connection, and any combinations thereof.

A digitizer (not shown) and an accompanying pen/stylus, if needed, may be included in order to digitally capture freehand input. A pen digitizer may be separately configured or coextensive with a display area of display device 865. Accordingly, a digitizer may be integrated with display device 865, or may exist as a separate device overlaying or otherwise appended to display device 865.

Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. It will be understood by those skilled in the art that various changes, omissions, and additions may be made to that which is specifically disclosed herein without departing from the spirit and scope of the present invention. 

What is claimed is:
 1. A control system for controlling the output of a combined cooling, heating, and power (CCHP) device, the control system comprising: a local data acquisition module configured to receive local inputs related to the operation of the CCHP device; a remote data acquisition module configured to receive remote inputs; and a data processing module configured to receive said local inputs and said remote inputs, said data process module generating outputs suitable to regulate the operating of the CCHP device based upon said local inputs and said remote inputs, wherein generating said outputs includes: compiling CCHP device user data profiles; predicting future CCHP device user demands based upon said user data profiles, said local inputs, and said remote inputs; and developing said outputs based upon said predicting.
 2. A control system according to claim 1, wherein said user data profile is an energy usage profile.
 3. A control system according to claim 2, wherein said energy usage profile includes a heat profile, a cooling profile, and an electricity profile.
 4. A control system according to claim 1, wherein said remote data includes user data.
 5. A control system according to claim 4, wherein said user data includes one or more of a heat demand, a cooling demand, a hot water demand, and an electrical load demand.
 6. A control system according to claim 1, wherein said remote data includes price data.
 7. A control system according to claim 1, further including a diagnostic module, said diagnostic module configured to receive information from said data management module suitable for evaluating the operating conditions associated with the CCHP device.
 8. A control system according to claim 1, further including a data processing unit configured to determining, based upon said local inputs and said remote inputs, operating parameters for the CCHP device, wherein said determining includes evaluating the cost of operating the CCHP device relative to other available power and/or heat sources.
 9. A combined cooling, heating, and power (CCHP) device for a structure coupled to an energy source comprising: an energy generator; a waste heat recovery system designed and configured to recovery thermal energy from said energy generator, said waste heat recovery system having at least two modes of operation; wherein in a first mode of operation said waste heat recovery system uses said recovered thermal energy for the structures thermal needs, or stores the thermal energy from said energy generator, and wherein in a second mode of operation said waste heat recovery system uses the stored thermal energy to cool ambient air; and a control system for controlling said energy generator and said waste heat recovery system, said control system configured to determine a need of the structure and to evaluate whether said need should be met by one or more of said energy generator, said waste heat recovery system, and the energy source.
 10. A CCHP device according to claim 9, wherein said energy generator is a fuel cell.
 11. A CCHP device according to claim 10, wherein said fuel cell is a polymer electrolyte membrane fuel cell.
 12. A CCHP device according to claim 9, wherein said waste heat recovery system includes a thermal management module, a storage system, a distribution system, and a cooling system.
 13. A CCHP device according to claim 9, wherein said control system is configured to control the outputs of said energy generator and said waste heat recovery system so as to utilize about 100% of the electrical and thermal energy produced by said energy generator.
 14. A CCHP device according to claim 9, wherein said control system includes: a local data acquisition module configured to receive local inputs related to the operation of said energy generator and said waste heat recovery system; a remote data acquisition module configured to receive remote inputs; and a data processing module configured to receive said local inputs and said remote inputs, said data process module generating outputs suitable to regulate the operating of said energy generator and said waste heat recovery system based upon said local inputs and said remote inputs, wherein generating said outputs includes: compiling user data profiles; predicting future user demands based upon said user data profiles, said local inputs, and said remote inputs; comparing a cost, based upon said predicting, of generating energy using said energy generator, said waste heat recovery system, and the energy source; and developing said outputs based upon said predicting and comparing.
 15. A method of optimizing energy sale and consumption for a distributed fleet of customers having combined cooling, heating, and power (CCHP) systems, the method comprising: collecting customer dependent from each of the distributed fleet of customers and independent information; predicting fuel consumption by each CCHP system based upon said collecting; predicting electricity needs of each of the distributed fleet of customers based upon said collecting; determining gross fuel-consumption and electricity needs of distribute fleet based upon said collecting, said predicting fuel consumption, and predicting electricity needs; negotiating fuel purchases based on said determining; negotiating electricity purchases on said determining; and managing fuel usage of each CCHP system in the distributed fleet based upon actual customer needs, said negotiating fuel prices, said negotiating electricity prices.
 16. A method according to claim 15, wherein said predicting fuel consumption includes analyzing past fuel usage information of each of the distributed fleet of customers.
 17. A method according to claim 15, wherein the CCHP system includes an energy generator and a waste heat recovery system, and wherein said managing includes: determining a cost of operating a first CCHP system in the distributed fleet; comparing the cost to said negotiated fuel prices and said negotiated electricity prices; operating the first CCHP system based upon said comparing.
 18. A method according to claim 17, wherein said comparing includes evaluating the availability of a low-cost power source.
 19. A method according to claim 18, wherein the low-cost power source is one or more of a solar panel, a wind turbine, and a hydro-turbine.
 20. A method according to claim 17, wherein the energy generator is a fuel cell. 